The field of the disclosure relates generally to a gasifier, and more specifically to a system and method for switching fuel feeds during a gasifier start-up.
At least one known gasification system, such as an integrated gasification combined-cycle (IGCC) plant, includes a fuel supply system that is coupled upstream of a gasifier and that is configured to channel fuel to the gasifier. At least one known fuel is a slurry of powder coal and water. In such a system, the slurry is a viscous liquid that is metered within the fuel supply system and that is delivered at a predetermined pressure to the gasifier.
In some known IGCC systems with slurry fed gasifiers, a two-step process may be used for gasifier start-up that includes establishing steady flows of all feeds in bypass and/or start-up conduits not connected to the gasifier, and redirecting the flows into feed conduits connected to the gasifier feed injector according to a prescribed sequence. The start-up slurry flow in a slurry feed system is established in a circulation loop that returns to the original slurry storage tank, and the start-up oxygen flow may be vented to atmosphere through a silencer. In conventional systems, upon start-up, the slurry and oxygen flows are diverted into the gasifier so that the oxygen reaches the feed injector a short time after the slurry. The thermal energy stored in the preheated gasifier refractory brick ignites the reaction mixture and the gasification reactions begin.